1. Field of the Invention
This invention relates to a colloidal mill specifically designed to mix a premixed mortar in a high energy manner so as to provide a high degree of hydration.
2. Description of the Prior Art
As is well recognized in the construction and building industry concrete is used generically to define a collection or aggregation of materials which together form a reasonably continuous and consistent solid when cured. In conventional applications of concrete products voids, and/or small discontinuities or inclusions of air within the resulting product, are considered to be highly underdesirable. This is true since such voids normally affect the operating or performance characteristics of the product in a harmful manner.
However, in a certain specialized category of concrete such voids are intentional for the purpose of producing what is known as a porous concrete. While porous concrete is generally well known in the prior art such products frequently suffer from inherent problems, such as a weakness or a lack of structural integrity, which makes the overall product relatively undesirable.
The following U.S. Patents disclose prior art products and/or methods of forming concrete products or cementitious material which is generally applicable but clearly distinguishable from the product which is formed through the utilization of the machine or assembly of the present invention: U.S. Pat. Nos. 2,710,802 to Lynch; 3,582,88, to Moore; 1,665,104, to Martienssen; 3,196,122 to Evans; 3,240,736, to Beckwith; 3,360,493, to Evans; 3,429,450 to Richards; 3,477,979, to Hillyer; 3,687,021, to Hinsley; 3,690,227, to Weltry; 3,870,422, to Medico; 2,130,498, to Klemschofski; 3,822,229, to McMaster; 954,511, to Gordon; 2,851,257, to Morgan; 3,877,881 to Ono and 4,225,247, to Hodson. Additional prior art can be found in U.S. Pat. Nos. 666,001, to Ditto; 1,670,714, to Craig, and 1,927,620, to Tolman.
The products of the type generally disclosed in the above set forth U.S. patents frequently suffer from certain inherent disadvantages. Such disadvantages include failure under heavy load or stress conditions as in highway construction. However, there is an acknowledged need in the construction industry, especially in the area of building roads, highways, bridges, etc. for a porous concrete type product. Such preferred porous contrete product should further be able to stand high load or stress conditions for high speed operation of large or heavy motor vehicles. Other uses of a porous concrete product are available once the desirable performance and operating characteristics of such a product has been established.
In previous concrete, a high shear mixer produces a cementwater component of high strength and increased viscosity. This results in a high strength structure in the final discontinuous concrete. However, the process of combining or mixing cement and water can be carried much further, although not necessarily of benefit in pervious concrete, since a greater intensity of fine particle mixing produces a cement-water combination of paint-like consistency, which sets to a glass-like surface, not appropriate to pavement.
However, with proper techniques, such a super-mixed mortar can be directly sprayed, painted or otherwise applied to cement products, and with proper curing processes produces a gloss finish surface which is more durable than normal concrete, and which has an appearance similar to glazed ceramic tile. By the use of white cement (in place of grey) and standard and organic mineral colors, many decorative effects can be obtained. Experience has shown that the surface produced is extremely durable, although its Mohr hardness value is below the level of kiln-fired ceramics. For example, it can be scratched by martensitic steel if a blade or tool is applied with sufficient pressure, or by abrasion with silicon compounds.
In explanation of this result, it appears that, in general, high energy mixing further colloidalizes the cement, water fraction, and produces a new mortar form proportional to the intensity of mixing which results in combination and hydration at much finer particle sizes than is accomplished by present mixing methods. It should be noted that the limitation of particle fineness in cement clinker grinding during production, as presently practiced, is to prevent shrinkage, surface crazings, and cracking thought to be a hydration effect.
However, the colloidalized mortar shows no signs of such defects. Apparently, the colloidalizing process accelerates exothermic behavior so as not to protract heat loss and shrinkage factors in the setting phase. At the same time it appears to produce more of the strength intrinsically available from the hydration of cement as indicated by the know quality to re-grind set concrete, which may then be mixed with water, when it will again generate some setting strength illustrating its full potential is not reached in normal concrete practice.
Assuming a strength increase as high as may be expected from recognized re-grinding and remixing data, it should be possible to considerably reduce the cement content of concretes and still obtain, comparable strengths. In adition, this idea can be extended to the use of pozzolanic additives, particularly fly ash, which is a by-product of coal-fired furnaces. This will further reduce the cement consumption. It may ultimately be possible to use a lime and fly ash to completely replace cement, without the use of partial fusion, as now practiced in cement production.
It is readily believed that the inherent deficiencies set forth above are due to a failure to fully form the hydrated product when utilizing conventional or currently known techniques as in the formation of substantially conventional concrete or the like. Accordingly, there is an obvious need in the industry for mechanisms and processes of forming concrete utilizing conventional cement, water and aggregate components in a manner which will result in more favorable operating and performance characteristics.